Beautiful looking lush green Lawn, how to ?

[Saltire]

Whats the best way to get a really nice vibrant green Lawn ?

We have a massive garden area nearly the size of a 5 a side football pitch, plus another two smaller gardens too, so plenty of lawn to be looked after.

Over the years we have tried several different types of fertalisers usually always to find that after a day or two the lawns have lots of scorched patches that the fertaliser has obviously burnt the grass etc.

Spoke to a gardener and he says that he gets his lawn perfectly green and great looking by spreading some type of sand over the lawn after it is cut and then watering the lawn well, but I have never heard of that method and I wouldnt even know what type of sand he meant and I forgot to ask him.

Anyways, does anyone have any ideas please ?

(p.s, trying to keep it nice and simple too because of the sheer size of the area's of lawn as I mentioned).